Conventionally, so-called fluorescent observation has been widely performed, including, in a microscope system, radiating a light of a specific wavelength to an observation target to which a fluorescent reagent is applied to thereby excite the fluorescent reagent and detect and observe fluorescence emitted from the observation target, and, in an endoscopic device, detecting or observing fluorescence emitted from a living body by a light of a specific wavelength being radiated to an observation target.
In the fluorescent observation, in order to efficiently detect fluorescence from the observation target, it is necessary to radiate a light having a wavelength according to excitation light characteristics of the fluorescent reagent or the living body. Because the excitation light characteristics differ for each fluorescent reagent or living body, an illumination apparatus applied to the microscope system and the endoscopic device is configured to be able to perform illumination with lights of a plurality of different wavelengths according to various excitation light characteristics.
PTL 1 discloses one example of such an illumination apparatus which includes three light sources (LEDs) and two dichroic mirrors, and which can output a light while selecting a wavelength of a light to be radiated to an observation target by switching the light sources appropriately and synthesizing colors of a plurality of wavelengths using the dichroic mirrors.